storcon: do graceful migrations from chaos injector

[jcsp]

Problem

Followup to #10913

Existing chaos injection just does simple cutovers to secondary locations. Let's also exercise code for doing graceful migrations. This should implicitly test how such migrations cope with overlapping with service restarts.

Summary of changes

[github-actions]

7766 tests run: 7377 passed, 11 failed, 378 skipped (full report)

---

Failures on Postgres 17

• test_storcon_cli: release-x86-64-with-lfc, release-x86-64-without-lfc, release-arm64-without-lfc, debug-x86-64-without-lfc, release-arm64-with-lfc

Failures on Postgres 16

• test_storcon_cli: release-x86-64-with-lfc, release-arm64-with-lfc

Failures on Postgres 15

• test_storcon_cli: release-x86-64-with-lfc, release-arm64-with-lfc

Failures on Postgres 14

• test_storcon_cli: release-x86-64-with-lfc, release-arm64-with-lfc

# Run all failed tests locally:
scripts/pytest -vv -n $(nproc) -k "test_storcon_cli[release-pg14] or test_storcon_cli[release-pg14] or test_storcon_cli[release-pg15] or test_storcon_cli[release-pg15] or test_storcon_cli[release-pg16] or test_storcon_cli[release-pg16] or test_storcon_cli[release-pg17] or test_storcon_cli[release-pg17] or test_storcon_cli[release-pg17] or test_storcon_cli[debug-pg17] or test_storcon_cli[release-pg17]"

Test coverage report is not available

_{The comment gets automatically updated with the latest test results
ea2ddf8 at 2025-02-27T19:55:28.635Z :recycle:}